1. Field of the Invention
The present invention relates to MAP transmission in a wireless communication system. More particularly, the present invention relates to a method and an apparatus for transmitting MAP information through randomization and Cyclic Redundancy Check (CRC) masking in a broadband wireless communication system.
2. Description of the Related Art
In an Institute of Electrical and Electronics Engineers (IEEE) 802.16m communication system, a base station transmits a resource to be allocated or used by each mobile station and transmits information used for data transmission and reception through an assignment Advanced-MAP (A-MAP) Information Element (IE) in downlink and uplink.
The assignment A-MAP IE includes information used for operating a mobile station. Using a predetermined seed value of randomization and a Cyclic Redundancy Check (CRC) mask value, the base station transmits the assignment A-MAP IE to the mobile station. Each mobile station identifies the given assignment A-MAP IE using the predetermined randomization seed value and the CRC mask value. The seed value of the randomization uses 15 bits excluding a 1-bit masking prefix in the 16-bit CRC mask value. When the predetermined randomization seed value and CRC mask value are determined, a STation IDentifier (STID) value of the mobile station is a critical value that is to be secured.
However, security is vulnerable to a malicious mobile station which obtains the assignment A-MAP IE information assigned to another mobile station using a STID other than its own STID. That is, since the STID includes 12 bits and has only 40,912,266 different values, anyone may acquire the STID of the other mobile station and easily obtain the assignment A-MAP IE information assigned to the other mobile station.
Thus, the data transmission may be vulnerable to a security breach when the malicious mobile station obtains the allocation information of data of the other user transmitted in the downlink through the assignment A-MAP IE of the other user terminal and then receives the data at the malicious mobile station. To address this problem, the present invention provides a method and an apparatus for more safely transmitting the assignment A-MAP IE.